When packaging an article into a container, and when the container is to be used for articles having several sizes, empty space exists between the article and the walls of the container. When shipping the container holding the article, movement of the article in the container should be restrained in order to prevent damage of the article.
In particular, when packaging a stack of sheets, especially photographic or thermographic sheets, it is customary to use a set of flat rectangular containers, having a limited number of sizes, for packaging stacks of single size sheets having many possible sizes. A container with a specific size may e.g. hold sheets of a first size, or sheets of a second size, or sheets of a third size. In this way, the required number of different packaging containers is reduced. This is especially interesting for less frequently called-for sheet sizes.
FIG. 1 shows a prior art container 10 having a base 11 and a cover 19 for the base. The base 11 has a bottom 12 and side walls 13, 14, 15, 16. To restrain movement of the stack of sheets 20 in the container 10 during handling or shipping, it is customary to fill the empty space between the sheets 20 and the side walls with strips of shock-absorbing material 81 and 82, e.g. strips of foamed polyethylene. A drawback is that the strips are cut manually, which is labour-intensive and time-consuming, and which generates dust and dirt.
Patent application EP-A-0 597 545 discloses a reusable container for packaging graphical sheet materials. The bottom of the container has channels; chocking elements can be inserted in the channels to allow sheet materials of varying sizes to be accommodated in the same container. Disadvantages are that an expensive container is required and that only those sizes of sheet materials can be accommodated for which channels are foreseen.
Patent application GB-A-2 304 332 discloses a container for film sheets, shown in FIG. 2. The container has a base 11, shown in FIG. 2a, and a cover for the base, not shown. The container has a chocking element 91, that is attached to the bottom 12 of the base 11, at an arbitrary location, and that restrains the film sheets 20 from moving relative to the bottom of the container. FIG. 2b shows the chocking element 91 more in detail. A suitable chocking element is thermoformed, and made of a high impact polystyrene having a thickness of approximately 1 mm. This container represents several disadvantages. The chocking element is rather expensive. It is difficult to remove the chocking element from the container without damaging the bottom of the container. This is a drawback if the container has to be reused for packaging sheets having a different size.
The present invention is particularly intended for packaging a stack of sheets into a container without these disadvantages; the present invention is however also applicable to packaging a substantially flat article into a container.